Multicomponent analysis of volatile organic compositions in vapor samples

Abstract

Amounts of volatile organic compositions can be evaluated from vapor samples based on the time dependent response of a fuel cell contacted with the vapor sample at its anode. The time response of the fuel cell signal, e.g., voltage or current, is de-convoluted using a set of standard curves for an equivalent fuel cell configuration obtained separately for each of the volatile organic compositions of a fuel cell with an equivalent construction as the sample-evaluation fuel cell. The methodology can be implemented on a system with an appropriate vapor collection device suitable for the particular application. The method and system can be used to analyze breath samples to evaluate ethanol levels or other volatile organic composition. The system can be a breathalyzer, a vehicle interlock, a medical analysis device or a sensor of environmental or industrial interest.

1. A system comprising:
 a sample collector; 
 a flow apparatus that is configured to receive a sample from the sample collector; 
 a fuel cell comprising an anode connected to the flow system apparatus wherein the sample transported within the flow system apparatus contacts the anode; and 
 an analyzer that receives a signal related to a signal from the fuel cell, and evaluates the amounts of a plurality of volatile organic compositions from the time response of the fuel cell signal as a function of time from a de-convolution of the time response of the fuel cell based on separate standard time response functions from each of the volatile organic compositions, 
 wherein the fuel cell comprises an electrolyte comprising a perfluoronated, sulfonic acid polymer, 
 wherein the anode comprises a plurality of particles comprising platinum and carbon, and 
 wherein the anode comprises a porous, conductive carbon cloth gas diffusion layer. 
 
     
     
       2. The system of  claim 1  wherein the sample collector comprises a mouthpiece. 
     
     
       3. The system of  claim 1  wherein the flow system apparatus comprises a pump that facilitates control of the flow through the flow apparatus. 
     
     
       4. The system of  claim 1  wherein the fuel cell comprises an ionomer as the electrolyte. 
     
     
       5. The system of  claim 1  wherein the analyzer comprises a microprocessor. 
     
     
       6. The system of  claim 1  wherein the analyzer performs a linear fit of the standard curves to approximate the sample time response. 
     
     
       7. The system of  claim 1  wherein one of the volatile organic compositions is ethanol and another of the volatile organic compositions is a component of tobacco smoke. 
     
     
       8. The system of  claim 1  wherein the system is a portable unit. 
     
     
       9. The system of  claim 1  wherein the system further comprises an interface to a vehicle ignition system and wherein the analyzer prevents ignition of the vehicle engine if a volatile organic composition is measured above a selected value.